Abu Dawud Book 8, Hadith Number 2524.
Chapter : Not known.
Narated By AbuSa’id al-Khudri : A man emigrated to the Apostle of Allah (PBUH) from the Yemen. He asked (him): Have you anyone (of your relatives) in the Yemen? He replied: My parents. He asked: Did they permit you? He replied: No. He said: Go back to them and ask for their permission. If they permit you, then fight (in the path of Allah), otherwise be devoted to them.